Data regarding operation of a vehicle is often stored to a memory device, or simply, a “memory”, for later retrieval and use. One common technique for storing such data is a circular buffer where the data is recorded sequentially at a defined rate. After each recording, the address of the memory storage location is incremented, so that the memory fills up sequentially. When an upper limit of the memory is reached, the address is reset to a beginning location and data is over-written from the beginning location. The memory addresses to be written to can be expressed as:Adds=Addmin+Ts mod n wherein Adds is the current address that is being written to, Addmin is the minimum (or beginning) memory address, Ts is an incrementing time sample (e.g., 0, 1, 2, 3, . . . ), and n is the number of memory locations. In this application, the notation “x mod n” will refer to the remainder of the quantity x divided by n.
One drawback of this technique is that all of the data is written at a single sampling rate. Therefore, a large memory device is required to record data for a large period of time while providing for a fast sampling rate close to an event, e.g., an airbag deployment event.
To save on the amount of storage locations that are required in a memory, it may be beneficial for older data to only be retained at a slower sampling rate while still maintaining the fast sampling rate near the event.
Accordingly, it is desirable to provide systems and methods that allows for storing data at multiple sampling rates. Furthermore, other desirable features and characteristics of the present invention will become apparent from the subsequent detailed description and the appended claims, taken in conjunction with the accompanying drawings and the foregoing technical field and background.